See our FAQ[1] on why we forked. As three years passed and both projects are actively developed, the divergence has grown a lot since. We aim for exposing the proper API instead of relying just commands, see e.g. our new Python bindings and rz-bindgen[2]. We have completely different concept of projects, new intermediate language - RzIL[3], and many other things. And under the new organization Cutter is a first-class citizen, not an afterthought as before.